Fracture analysis of vehicle-mounted telescoping communications mast

In this paper a fractured connector plate for a telescoping antenna mast made of aluminum alloy EN-AW 2007 was examined. The goal of the investigation was to determine the cause of fracture which occurred during attempting to raise the antenna. Specimens taken from the mast were visually examined, and the fracture surface was examined using a scanning electron microscope. Chemical analysis, microstructural analysis, electrical conductivity measurements, tensile test and hardness test were performed in order to investigate the properties of the material. Fracture occurred fast and visual and fractographic examinations showed that there is no visible plastic deformation near the fracture surface, which are characteristics of a quasibrittle fracture. It was shown that the mechanical properties of the examined specimens do not satisfy the minimal values defined in the standard for this material. All conducted tests indicated that the material had not been heat treated and mechanically worked, so applied stress during handling/raising the antenna led to the rapid quasibrittle fracture.